Transmission-equalization arrangement



L. HIDARROW. TRANSMISSION EQUALIZATION ARRANGEMENT.

. 7 APPLICATION FILED OCT-2, I919 1,415,868.

Patented May 16, 1922.,

'lillll 9 mmvmk l). H Barron BY ATTORNEY L. H. DARROW. TRANSMISSION EQUALIZATION ARRANGEMENT.

1,415,868. APPLICATION FILED OCT-2, 19m. Patented May 16, 1922' 24SHETS-SHEET 2.

FEE

IN V EN TOR.

(9 ATTORNEY lone lines.

, UNITED STATES PEENT OFFICE.

LEO Hi DARROV, OF NEW YORK, N. Y., ASSIGNOR TO AMERICAN TELTEPI-IONE AND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK.

TRANSMISSION-EQUALI ZAIIQN ARRANGEMENT.

Specification of Letters Patent. Patented lay 16, 1922.

Application filed October 2, 1919. Serial No. 323,013.

Be it known that L lino H, Dirnnow, residing ut li'eu' York, in the county of New Yuri; and State of New Yorit, iiia've invented certain lmmovements in 'llransinissionltquaiiz iatiozn i irrangeineuts, oi which the :i oiiowing; is a specification.

This invention relates to telephone systenu-z and n'mre particuiarly to the provision o'i' nieuir-i whereby the electrical characteristics oi lIGlPPlIOlll: lines may he equalized or rendered nore 'ijiniitorm.

ihonn lines have, in general, diflerent .al riuimuiteristics varying With the is at the i ines. For any :)articuia1.' type oi lino ioiistruction which may he employed the l'tiili-iiitilltdi canncity, .iiuluctance and. leakrigeio'i the nircuit increase with the length. lho:-1e variations inthe eh' ctri ai character jii-tticsoi the ditierent subscribers lines in a teli-iphone :syetoin introduce a i'nnnher oi. vi

.rinliiie eii'lrrts in the telephone service renderoii iroin dii'ierent stations. For exainple the di'ilerent electrical characteristics rer-iuit in iiiiiereui degrees of attenuation in the alteiuniiin teieoiuine current passing over the euir-icrihoi lines and thus give loiuier and more e'ii'ective telephonic coi'i'imitinication to suliscriiiers count-u, id by means of short lines than to suin- -i'iiierscoi'inected by means oi? its a result. a suhscriher having a long: line, when couiu-mted with aiuyother subscriber. does not receive as good. telephone tiaiieu as would a suhscrilier having); a short line similarly connected. l urthcrniore. in the common battery systems: now so -enorally employed in all but email communities, the resistance oi theline miners a further eii ect on the trui'isnniesion in that it rediuw: the :unount of direct current which the transmitter receives from the central o'iiice battery and so renders it less citirient in the generation oi? the :iiteri'latii'ur telephone current, liihewise in connnonliat tery systems employing; electroanugnetic re- ('UiXtilS this variation in current supply intrmiuces clunn os inthe eiilcieney oi the re icei or which are un di'isirahle.

in View oi to it has not been heretofore possible to provide all sul'iscrihers with the same grade of transinissimi and it one of the objects of this invention to provide means whereby this (iii'iiculty may he inusrcoine and transmission over diiierent lines equalized. Other and the conditions above inferred further features oi the invention will appear from the description hereiiiaii'ter given.

In the arrangements of this invention the transmission equalizing means are aseociuted with the conne 15; means, ouch for example as a cord circuit or other means, by which connections are established with the lines rather than With the lines themselves as in :toriner arrangements. Associated with the coin'iecting niiai'is or cord circuit is appa ratus, such as a relay, which is so arrangiged that, when the cord circuit is connected With a line ELtlOptGll as a standard with respect to resistance, it Will not operate. when thecord circuit is connected to lines having resistzu'ices other than that of the stainlard line, the current flow over such lines will be greater or less than over the standard. line and will. operate the relay device. The relay device may be arrai'iged to operate other relay means to add to or subtract series resistance elements from the line until the resistance of the iinehas been made the same as that of the etaiu'lard line. The vice. The relay device may be arranged to operate other relay means whereby the voltage oi the i peratin current may he in creased or decreased in propm'tion to a m JiutiOil in the r(- s-iistance oi? the line :ironrthat oil the standardline. Finch arrangeine atl'ord a means For ei ualizhnz trzmsni' over suhi-icrihers lines of different long 1 or re istance values and -tor tieriug; ni'ore unitorni transmission over such lines.

The invention may he more i 'uiiy nndeu l in portion o if a cord circuit which is need in estahiishil'ig connectionev with suhscrihere lines such as the line L a portion of which is shown terminating in the jack J The cord circuit termiinites intho plug; P and in the tip and ring COIHlIlCLOiE 1 and 2 of the cord are a plurality of resistance elements such as R and R These resistance elements are controlled by the rel ay 6 which is oil? the non-stop type; that is the contacts t and 5 of relay 6, which are mounted on a gem, mechanism 3, always turn in one directihn,

iii)

sleeve, contacts of jack J and plug in to the jack J with the plug P y will close the following circuit: from ground and operate so as to short circuit the resistance R and R until all of them are short circuited, and then operate to connect all the resistances. in series again, repeating the process. With this arrangement the resistance included in series in the conductors 1 and 2 maybe varied. The relay 6 is controlled by the relay 7, the windings of which are arranged differentially for purposes which will be more fully pointed out hereinafter. Associated with the sleeve conductor of plug P, is the relay 1.0, which controls the supervisory signal 11, which in turn is further controlled by the linerelay 12. The relay 7 controls the circuit for the relay (3, which circuit is completed through an interrupting. apparatus 13, so that the relay 6 will operateintermittently.

The arrangements in Fig. 2 are substantially the same as those in Fig. 1, except that. the relay 6 serves to control the voltage of the battery supply 9 rather than the series resistance of conductors 1 and 2.

In the arrangements illustrated in Fig. 3,

the relay 7 controls the operation in se quence of the relays 14, 15 and 16, which relays in turn determine the number of series resistance elements, such as resistances R R R R R and R which should be in- 30 cluded in the conductors 1 and 2.

. In Fig. 4 the relay 7 controls the operation in sequence of the relays 14:, 15 and 16, which relays in turn control the amount of current supply which should be app-lied to the conductors 1 and2. 1

In the arrangements illustrated in Fig. 5 are shown series resistance elements R and R, included in conductors 1 and 2. These resistance elements are controlled by the relays 22 and 23, and the gear mechanism 3. The relays 22 and 23 are controlled by an ammeter relay 20 which responds to varia tions in the amount of current transmitted over the line.

. The invention may he more fully understood from the following description of the operation of the arrangements illustrated in Fig. 1. When a subscriber on a line such as L originates a call, and his line signal lights, the operator will answer by plugging This associated with the sleeve of the 'aclr J conductor 30, winding of relay 10 to battery and ground. This will operate the relay 1i) and thereby close the following circuit: from ground and battery, armature and contact of relay 10, conductor 31, signal lamp 11, contact and armature of relay 12 to ground. However, the signal lamp 11 will not light, as this last mentioned circuit will be held open by the relay 12, which operates over the following circuit. when the plug: P is inserted in the jack J from ground, battery 9, conductor 32, left hand winding of relay 7, conductor 33, tip conductor of the cord, resistance elements 11, conductor 1, tip contacts of plug P, and jack J tip conductor of the line L,, through the subscribers substation apparatus, ring conductor of line L ring contacts of jack J, and plug P conductor 2, resistance elements .h ring conductor of the cord, conductor 34-, winding of relay 12 to ground. This circuit will operate relay 12 and close the following circuit: from ground, battery 9, conductor 32, right hand winding of relay 7, conductor 35, contact and armature of relay 12, to ground. As has been formerly pointed out, the windings of relay '7 are arranged diil erentially and are so adjusted that when the cord cir cuit is connected with a line whose resistance is taken as a standard, the currents flowing through both windings will be equal and the opposing fluxes set up in the core of relay 7 will be equal and neutralize each other. However, it the cord circuit is connected with a line having a resistance other than that taken as a standard, the currents flowing through both windings will not be equal and the flux caused by the left hand winding of relay 7 will not be equal to the flux caused by the right hand winding, and the relay 7 will operate. The operation of relay 7 closes the following circuit: from ground, contact and armature of relay 7, conductor 36, winding of relay (5, conductor 37, interrupter apparatus 13, to battery and ground. The closing of this circuit will cause relay 6 to operate intermittently, which will operate the gear mechanism 3 and cause contacts 4: and 5 to rotate. The contacts 1 and 5 will operate to short circuit more or less of the resistance elements 1% and ii, included in series with the previously traced circuit'including the left hand winding of relay 7, until the resistance of said circuit has been made the same as in the case when the cord circuit was connected with the standard line. At this point the currents flowing through tne two windings of relay T will be equal and the flux caused by the left hand winding will again be equal and opposite to the flux caused by the right hand lifi lllt) naiaeee.

the voltage ofthe battery Sl'lPPl lQdtO the following circuit :l'roni one of the termii'ials' of battery 9, conductor 38. winding: oi? relay 12, ring conductor of the cord, ring c-on tacts oi plug, P, and ack J over the ringr (JOIHlHUtUPOf the line, through the substation apparatus, over the tip conductor of the line,

, tip contacts of jackJ and plug 1 over the tip conductor oi" the cord, conductor 39, left hand winding of relay 7, conductor 40, contact il, to one of." th terminals otbattery 9. The closing of this circuit operates relay l2 and closes the following); circuit: from ground andbattery, right-hand winding-of relay 7, conductor 41, contact and armature of: relay 12 to ground; In the same manner as pointed out with respectto Fi 1,'the fluxes set up in the core of relay r by the differentially arranged windings thereof, will. neutralize each other when the cord connected with a standard line. but when the resistance oi? the line is other than standard. these fluxes will not neutralize each other, and. the relay 7 will operate. The operation of relay 7 will operaterelay 6 and the gear mechanism 3, and cause the contact 4: to rotate across the terminals of? battery 9, thereby ch ang ing the voltage oil the current supplied over the previously traced circuit including the subscribei"s line and the left hand winding of relay 7. soon as this current from battery 9 has in this manner been increased or decreased sufficiently so that the flux set up by the left hand winding of relay 7 is equal to the opposing); flux set up by the right hand gwinding thereof, the relay 7 will release, thereby 1'cleasiiu; the relay (3, and the proper amount of current will be supplied to the subscribers line to compensatefor any changes between the line and the standard line. i i

The principle of the operation of the arrangement illustrated in Fig. substan tially the sameas the arrangementin Fig. 1, in that the transmission iscqnalized by varying the amount of series resistance elements inchided in the talking circuit; 1 When a connection is made with a 'line'lutvina a resistance other than the standard, the differentially wound relay 7 will operate and close the following circuiti from ground and battery, contact and armature of; relay 7, conductor 47, contact 49, conductor 4-8, windinsr of relay 14;, to ground. The closing of this circuit will operate relay 1.4, which will a pull up its arm atures and close short circuits about the resistance elements ll and R thereby reducing the total resistance of the talking circuit. If this reduction in resistance is suiiicient to make the resistance of the talking circuit equal to that oi the standard talking circuit, the relay 7 will release. Relay 14: will be locked up over the following circuit 1. from ground, winding of relay let, conductor 18, contact 50, armature of relay 141;, condiurtor 58, conductorl3, con tact and. armature of relay 1.8, conductor 4-2, contact and armature of relay 1'? (which was operated wl'ien the plug P of the cord was inserted in the jack oi the line). to ljiattery and around. l'lowever, ii to reduce the resistance o'll'the talking circuit to a standard it is necessary to 'ti'irther decrease the re sistance of the circuit, the relay T will not release. Accordingly, upon the operation of relay 14". the following circuit will also be cou'ipleted: from. ground andv battery, contact and .armatuir oi. relay .7, conductor 47, contact 51, condi'u-tor 52. contact 5?, conductor 55, winding of. relay 15. to ground. This will operate relay 15, which will. close short circuits about resistance elements It, and R and furtheii' reduce the resistance of the talkinncircuit. In case the subscribers line is a party line, and the connection is made for one of the parties such as the party furthest from the central oliice, and while the connec: tion is up the party nearest the central oilicc removes his receiver from the switch hook, the cord circuit will equalize the current supplied to the line, so that both transmitters in i parallel receive only the predetermined value of the current. ln case the second subscriber finding the line busy, should again hang, up, the current flow to the first schscriber would then. not be equalized. Relay 7 would then operate and remain. operated until all oi the relays l4, 15, etc, had been operated. hen th relay 16 operates, the i ollowina' circuit is closed from ground and battery, contact and armature o't relay '7, coiuluctor 47, contact- 51, conductor 59. contact 56,t()1l(lll0ll('llf 57. contact 63, condiu-tor (l-.1. winding of relay 18. to ground. This will. operate relay 1.8 which will open at its contact the previously traced locking circuits for the relays l l, and 16. All oi? these relays then release and. the process of short circuitiiur the r stance elements starts in again from relay 14., and continues until the proper balancing point For relay 7 is reached. While only three relays. such. as relays 14, 15 and 16 have been illustrated, and only the resistance elements R ll, R Ilgpll, and R it is understood that a greater or smaller number of relays and resistance elements similarly arranged may be employed.

In the arrangements illustrated in Fig. 4-, the operation is substantially similar to the arrangements oi l 3. However, the relays 14. 15 and 16 do not control the current supplied to the circuit by means of varying the resistance of the circuit, but rather by adding in series with battery 9 the batteries 70. '71 and 7 2 respectively.

In the arrangements illustrated in Fig. 5,

an ammeter relay 20 is employed in place of the differentially wound relay 7 of the other figures. The ammeter relay 20 is adjusted so that when the cord is connected with a line of standard resistance, it will not operate. However, should the cord be connected with a line having a resistance greater than standard, less current would flow through the ammeter relay, and the armature thereofcwould be deflected to the left, thereby closing the following circuit: from ground, armature and make contact of relay 21 (which operated when the cord was connected with the line) over conductor 73, armature and left hand contact of relay 20, conductor 74, winding of relay 22, conductor 75, interrupter 13, to battery and ground. The closing of this circuit will operate relay 22 and the gear mechanism 3 whereby the contacts 4 and 5 will be rotated in a manner so as'to short circuit portions of the I resistance elements R andR in series with the talking circuit, thereby decreasing the resistance of the talking circuit until it is the same as that of a standard line, at which point relay 20 will release, This will release relay 22 and causethe aparatus to'stop operating. In a similar manner, if the cord is connected with a line having less total re sistance than a standard line, the armature of relay 20 will be deflected to the right, and acircuitjcompleted through relay 23. This will cause the contacts 4 and 5 to rotate in a manner so as to increase the resistance elelephony such as in district or incoming selectors in such systems. Accordingly while the arrangements of the invention have been disclosed in certain specific arrangements which have been deemed desirable, it is understood that they are capable of embodiment in many and widely varied forms without departing from the spirit of the invention as defined in the appended claims.

What is claimed is:

1. In a telephone exchange system, subscribers lines of differing electrical characteristics, a connecting means for establishing connections with said lines, a source in said connecting means for supplying talking current for said lines, a differentially wound relay in said connecting means, one of the windings of said relay being included in the talking circuit of said connecting means and a line, the other winding being included in a local circuit, said local circuit being so adjusted that when said talking circuit includes a line of predetermined elem trical characteristics said relay will not open ate, and means controlled by said relay for varying the current flow from said source over said talking circuit.

2. In a telephone exchange system, subscribers lines of differing electrical characteristics, a cord circuit for establishing connections with said lilies, a source in said cord circuit for supplying talking current for said lines, a differentially wound relay in said cord circuit, one of the windings of said relay being included in the talking circuit of said cord and a line, the other winding being included in a local circuit, said local circuit being so adjusted that when said talking circuit includes a line of predetermined electrical characteristics said relay will not 0 erate, variable resistance elements include in the talking circuit of said cord, and relay means controlled by said di ferentially wound relay for controlling said variable resistance elements.

3. In a telephone system, Subscribers lines of differing electrical characteristics, a connecting circuit for establishing connections with said lines,avariable resistance included in series in the talking circuit of said connecting circuit, relay means in said connecting circuit responsive to variations in said electrical characteristics, and a step-by-step switch controlled by said relay tor controlling said variable resistance.

In testimony whereof, I have signed my name to this specification this 30th day of September, 1919.

LEO H. DARROW. 

